1. Field of the Invention
The present disclosure relates generally to the construction of and methods of construction of composite closures, such as entryway doors, bi-fold doors, and the like for openings between rooms in structures. More specifically, it relates to the construction of doors, including both single doors, bi-fold doors, and the like that allow for the doors to be constructed with increased strength, durability, and lifetime with the optional ability to be height modified so as to fit into an opening as necessary.
2. Description of the Related Art
As the market for customized homes and do-it-yourselfers increases, the demand for more decorative and architecturally interesting closures for openings, such as closets, cupboards, laundry rooms, linen closets, bath rooms and the like, have similarly increased. Various materials are used to construct architectural doors. Architectural wood doors are well known. Wood doors, however, when exposed to humidity in general (e.g., in humid climates, or in bathrooms), and especially when exposed to water, rain, snow, sun and other elements require frequent maintenance including the application of various stains and clear coats in order to prevent cracking, discoloration, deformation, and other similarly unwanted maladies. Wood doors can also warp and are subject to rot and insect damage, such as from termites. There is therefore a need for doors having low maintenance that are not susceptible to the elements. As a result of this need, various alternatives to wood have been developed and are available.
Doors having steel, aluminum, or other low-weight metals or bi-metals as facing panels or structural components are one of the common alternatives to wood architectural doors. While these metal panel doors are fairly inexpensive to construct and are somewhat dimensionally stable under temperature fluctuations, the initial start up costs associated with producing a metal door is high. High pressure tools are often required to form the panels. However, unless the metal panels used have a high thickness, doors constructed with metal panels are often subject to denting. Additionally, metal doors are often subject to oxidation and rust formation, which can adversely affect their aesthetic appearance and functionability. Similarly, due to the nature of their construction, metal doors often emit an unpleasant squeaking noise during their opening and closing, due to effects such as humidity and air oxidation of their working parts. In addition, imparting a crisp multi-directional wood grain appearance to a metal panel door to increase its aesthetic qualities is difficult and costly, and so this is typically not done.
Doors constructed with fiberglass facing panels are another, increasingly-common option. Fiberglass facing panels can have significant benefits over steel and other metals. For example, fiberglass facing panels can be constructed to resemble a panelized wooden door. However, such fiberglass doors are very expensive to construct. And, like steel or other metal doors, the start up costs associated with production is high and production rates are very slow. In example, expensive molds must often be used to produce the panels having a panelized wooden door appearance. The raw materials for fiberglass doors are also relatively expensive. Fiberglass doors also have problems with dimensional stability resulting from temperature fluctuations. Such dimensional instability may eventually damage a door, necessitating its (sometimes costly) replacement.
Traditionally, entrance doors to rooms, as well as bi-fold, half doors, and sliding doors (such as pocket doors) have been made of wood, but the ever-increasing cost of wood as lumber supplies decrease has caused the industry to search for other suitable materials. One economical approach has been with the use of aluminum for fabricating such door closures, due to the economics and the lightweight nature of the product.
However, while economical to make and produce, these lightweight doors suffer from a variety of problems similar to other metal doors as elucidated above, including low resistance to scratching and denting, and poor paintability characteristics. For example, the amount of force needed to dent or bend aluminum closures is relatively low compared to other approaches and materials, with such resultant malformations impacting both the aesthetics of the door as well as the operability of the door once it has been bent or dented. Additionally, such doors are typically available only in a limited number of colors, and cannot easily be painted in an acceptable manner or made to appear like real wood.
Several manufacturers have turned to fabricating such bi-fold type doors and standard doors from alternative materials, most commonly synthetic resins, using injection molding techniques, such as described in U.S. Pat. No. 3,985,175. However, the injection molding process is limited in its application. Typically, the injection molding process involves making two rectangular hollow pans and joining the pans together by the edges to form a hollow door. According to U.S. Pat. No. 3,985,175, particular types of door construction is described, wherein a front face is made of injection molded plastic and has reinforcing members on the back side but no back face. Such a construction, while serving to maintain rigidity, provides a door having only one good “facing” side. The resultant door is thus often considered to be unsuited for a wide variety of general applications in the home or office, where it is likely that both faces of the door will be in view.
Others have tried to use a number of composite materials to obtain the desired product. These materials, however, are often not suitable for use in the formation of composite doors from both manufacturing and product lifetime perspectives. For example, several issued patents have suggested the formation of structural members from a polymer and a large amount of wood composite material. The structural members are formed from a composite containing a large amount (30 to 50 wt-%) of sawdust along with 50 to 70 wt-% of a polyvinyl chloride polymer. The composite is reportedly first blended and then extruded into pellets. The pellets are then extruded into the desired structural member. The disclosed composite, however, is not suitable for use in the formation of many types of doors because the material can degrade when exposed to high temperatures. Furthermore, the use of the disclosed, specific composite requires additional manufacturing steps, and the composite must first be pelletized before formation into the final shape as a structural member. Finally, the final product does not have the appearance of real wood, further reducing its commercial appeal.
One of the main problems with full length doors made from injection molded plastic is their lack of rigidity. Therefore, there is a need in the industry for non-wooden doors, including both standard closures for rooms as well as bi-fold closures and sliding doors, which can be readily and economically produced for a variety of architectural openings, and methods for constructing such strengthened closures while maintaining economic integrity. There also exists a need for such alternative closures which are capable of being easily and efficiently tailored to the dimensions of the closure as necessary by the end use, similar to closures constructed of solid wood materials, while maintaining the same aesthetic qualities as they did prior to the custom tailoring. Similarly, it would be advantageous if such wood-alternative closures were capable of being painted or textured in order to provide the appearance of natural wood, increasing the aesthetics of the product closures.
This application for patent discloses polymer-wood composite closures which can be height-adjusted in a manner similar to that done with standard wood doors and closures, methods for making and painting such closures, and methods for their use.